Pencil
Desktop wireframing and prototyping app with stencil libraries and AI control through a local MCP server.
Free wireframes with AI assistants over a local MCP server.
Pencil is a GPL-2.0 desktop app for wireframes, mockups and diagrams. Version 4.0 adds an MCP server so assistants like Claude Desktop or Cursor can edit the canvas on your machine.
What it is
It provides a vector canvas with stencil libraries (shadcn/ui, Bootstrap, Material Design, iOS, flowcharts), and exposes tools such as insert_shapes and render_preview to MCP clients over 127.0.0.1.
Who it's for
It suits developers and UX designers who want quick wireframes locally. It does not suit teams needing cloud files, comments or shared libraries.
Key features
Stencil libraries
shadcn/ui, Bootstrap, Material Design, iOS and flowchart stencils.
MCP server
AI clients inspect and edit the canvas locally.
Vector output
AI creates editable vector shapes, not bitmaps.
Preview loop
render_preview lets an AI check its own layout.
Local only
Documents and MCP traffic stay on loopback.
Three platforms
Installers for macOS, Windows and Linux.
Up and running in 3 steps
Our honest verdict
What's great
- Fully local with no cloud sync or telemetry, per the README.
- Prebuilt installers on three platforms.
- AI output stays editable vectors.
- Version 4.0 shipped in October 2026.
Where it falls short
- No cloud collaboration or comments.
- AI features need an MCP-capable assistant you already use.
- GPL-2.0 means shared changes if you redistribute.
Pricing & license
Pencil is free under GPL-2.0. The only cost is any AI assistant subscription you connect; no paid plan is shown in the README.
Open remote AI-training roles
768 open remote AI-training roles, updated November 14, 2026; most pay $20–$175 an hour. Zekai lists them free; the application goes to the employer’s platform.
Alternatives
These reviewed AI tools do the same job instantly — from our scored directory.
Use it, or have us set it up
FAQ
Is Pencil free?
Yes, under GPL-2.0.
Does Pencil send my designs to the cloud?
The README says documents and MCP requests stay on your machine.
Which AI tools work with it?
Claude Desktop, Cursor, Antigravity and VS Code have built-in config snippets.
